"Robert11" wrote in message
...
Hello:

Might someone please describe the differences between Selcal and Acars
that
are apparently both
used by commercial aero for air to ground reporting messages ?

Any suggestions for good (free ?) decoders for either ?

Thanks,
Bob


Selcall is an abreviation for selective calling that allows a radio to be
muted until it is called. I use it on both UHF CB (in Australia) and on HF
with some private HF freqs. When used on freqs with multiple users, it is
an effective way to not have to listen to other users and not have the
annoying noise from the HF bands. There are different types of selcall, but
most these days will send both the number of the station they are calling
and also the callers ID number. Usually there will be a preamble (long
tone) at the beginning of the selcall followed by two musical tones (similar
to DTMF, but longer tones).
ACARS is a means of passing information - i.e. it is a digital data mode and
sounds like a lot of other digital data modes, but is used specifically for
aircraft to pass messages to a variety of groups (i.e. their technical or
operation guys).




Matt